Automatic gauge for liquid containers



1941- G. E. EWERTZ 2,230,137

AUTOMATIC GAUGE FOR'LIQUID CONTAINERS Filed April 27, 1938 2Sheets-Sheet 1 g borz/ E yer '62. 22y

n 1941- G. E. EWERTZ I AUTOMATIC GAUGE FOR LIQUID CONTAINERS Filed April27, 1958 2 Sheets-Sheet 2 Patented Jan. 28, 1941 UNITED STATES 2,230,131auromrrc canon ron uomn commas Gordon B. Ewertz, Elizabeth, N. .1.

Application April 2'1, 1938, Serial No. 204,523

This invention relates broadly toa same for liquid containers andparticularly to an electrically operated gauge which is automatic in itsaction.

The primary object of the invention is to provide an electricallyoperated gauge for liquid containers, as, for example, water in tanks,or, a liquid supporting other non-mixing liquids, as, for example, waterand oil, or other fluids having diflerent electrical resistances.

Another object of the invention is to provide an apparatus that may belocally and/or remotely operated and observed, and that makes possiblean accurate measuring 'of a liquid, as, for

example, water ballast in a submarine.

Still another object of the invention is to provide an apparatus whichhas no moving parts within the container, and which is independent ofthe Baum and salinity of the fluids inthe container. I

Still another object of the invention is to provide a gauge which isautomatic in its opera tion and which has an indicator embodied thereinwhich follows the level of the liquid in the container closely. As theapparatus is an electrically operated mechanism an importantconsideration in its operation is the elimination of electrolysis, andit is therefore an object of this invention to utilize a vacuum tube ortubes in the structure of the apparatus in such a manner thatelectrolysis in the container will be eliminated or be reduced to anegligible amount.

It is a well known principle that the plate current of a vacuum tube canbe controlled by a grid potential. The plate current increases as thegrid potential is made less negative to zero and from zero to a.positive potential. The relays in the plate circuit can thereby beoperated by a change of grid potential, and it is therefore an object ofthis invention to embody this principle in the structure of theapparatus.

The invention consists of an automatic gauge as set forth in thefollowing specification and particularly as pointed out in the claims.

Referring to the drawings:

Fig. 1 represents a diagrammatical illustration of a gauge embodying myinvention as applied to a storage tank forwater.

Fig. 2 is a side elevation of the mechanism for actuating the rotaryswitch and indicator.

Fig. 3 is a front view oi the switch arms.

Fig. 4 is a detail vertical section illustrating the manner in whichtheswitch arms are mounted and rotated.

Like numerals refer to like parts throughout 5; the several views of thedrawings.

In the drawings, 5 represents a container, as,

and from-the tank 5. As illustrated these electrodes consist ofinsulated rods of different lengths exposed to the fluids in the tankatdifferent levels therein, but it is evident that said electrodes may beof any desired construction provided they have contact points embodiedtherein which are exposed to the fluids in the tank, are located atdifferent elevations in the tank, and are insulated therefrom. They mayalso consist of plugs mounted at difierentlevels n a closed tube locatedin the tank, or said plugs may be mounted in the side of the tank, if itis so desired, without departing from the spirit of the invention. Theelectrode 8 is common to all of the circuits which include theelectrodes, and the tank 5 itself may be used as a common lead in placeof the electrode '8 if it is so desired.

The operating mechanism of the gauge may be located adjacent to thecontainer 5 or at a distance therefrom and is as follows: The electrodes8 to [5 inclusive are connected by wires It to 23 inclusive respectivelyto electric terminal members 24 to 31 inclusive respectively of a rotaryselector switch 32 which is mounted upon a suitable base 33, see Fig. 2.Another terminal terminal member is blank, having no wire connectedthereto for reasons hereinafter to be more fully set forth. I

The-terminal members 24 to 3| inclusive and 34 are all mounted upon aninsulating plate 36 con-- centric with the axis of a shaft 31 upon whichswitch arms- 38 and 39 are mounted to rotate in unison therewith. Thearms 38 and 38 are insulated from the shaft 31 by a sleeve 40 of in- Hsulating material, and are insulated one from another by a spacingcollar II to which they are attached and which is rigidly secured tosaid.

shaft. The switch arms 38 and 39 are positioned out of step one with theother as illustrated in Fig. 3 to simultaneously contact with adjacentterminal members of the switch 32. The shaft 31 is rotated at arelatively slow rate of speed by means of a split phase reversibleelectric motor 42 through a. speed reduction mechanism 43 mounted uponthe base 33. The shaft -31 has an indicator 4 fastened thereto which isarranged to register with a calibrated dial it.

The switch arm 38 during rotation is always in electrical contact withan electric conductor member 34 is provided for the switch 32, but saidtion or'the other.

.as a single tube having two grids and two plates,

and any type of vacuum tube having a grid-may be used in place of thetriodes illustrated.

Connected in.the plate circuit of the vacuum tube 53 by a wire 54 is asingle pole double throw relay 55, and connected in the plate circuit ofthe vacuum tube 49 by a wire 58 is a double pole.

double throw relay 51. The relays 55 and 51 are connected one to anotherby wires 58, 59, 60

and 6|; to a source of electric supply by means of wires 52 and 63; andto the electric motor 42 by means of wires 84, 65 and 66 in such amanner that when the same potential is applied to the grids 48 and 52 ofthe vacuum tubes 49 and 53 respectively the motor is rotated in onedirec- When, however, one grid has one potential applied thereto and theother grid has a diilerent potential applied thereto the relays 5'5 and5 1 are so wired that'the motor will not run in either direction. Anytype of reversi-ble electric motor with suitable relays may be used, oreven two motors connected together and wound to rotate the shaft 31 inopposite directions may be used.

The vacuum tubes 49 and 53 are supplied with the proper voltages by apower pack which'may consist of a transformer 51, a rectifier tube 68,an adjustable resistor 69, and filter condensers 18 and 1|; allconnected one to another in a well known manner and as illustrated inFig. 1. A switch 12 is provided in the line to a suitable source ofelectricity which for the setup illustrated is A. C. current, but it isevident that with a proper power pack or batteries the gauge may bearranged to operate from any source of electricity either A. C. or D. C.

The grid potential for the vacuum tubes 49 and 53 is applied to thegrids 48 and 52 respectively through the wire I 8 to the electrode 8 andvia the fluid of least electrical resistance to the other electrodeswhich in turn are connected to the switch 32 and throughthe switch arms38 and 39 connected to said grids. Either a positive or a negativepotential may be applied to the grid as circumstances and the element ofsafety may demand. In water storage tanks, as for example the waterballast tanks of submarines wherein electrolysis can create no hazard,the application of a positive potential will cause a minute current toflowv in the container, but it is kept at such' a low value that it cando no damage. In tanks, however, where volatile liquid fuels are stored,and wherein no electric current can be allowed, a negative potentialapplied to the grids eliminates the flow of current entirely, and theuse of the gauge of this invention introduces no hazard to the handlingof the fluids.

The general operation of the apparatus hereinbefore specificallydescribed is as follows: Assuming that the level of the water in thecontainer 5 is as indicated in Fig. 1; that the other fluid in thecontainer is air; that the electrodes 39 are in engagement with theterminals 38 and 3| respectively; the indicator 44 of the dial 45 gagethe terminal members of the switch 32 is stationary at a location whichindicates the uppermost electrode that is submerged in the conductingfluid, viz. the water in the container. Under these conditions if apositive potential is applied to the grid of the vacuumtube 49 5 theplate current of said tube is raised and the relay 51 is closed. Under.the same conditions the electrode 15 being in the non-conducting fluid,viz. the air, a zero potential is applied to the grid 52 of thevacuumtube 53, the plate cur- 1 rent of said tube is low, and therelay 55 isopen. With the relays in these positions no electricity is applied tothev motor and it is therefore stationary. If for any reason the waterlevel in the tank is raised until it touches the electrode 15 l5, apositive potential is applied to the grid 52 of the vacuum tube 53, theplate current of said tube rises and the relay 55 closes, whereupon themotor 42 is energized thereby causing the switch arms 38 and 39 to berotated slowly in unison with the shaft 31 until the arm 38 contactswith the terminal member 3| and the arm 39 contacts with the isolatedterminal member 34 thereby breaking the electric circuit through saidarm. At this time a zero potential is applied to the 2 grid 52 of thevacuum tube 53, the plate current of said tube drops, the relay 55opens, and the motor 42 stops after having moved the indicator 44 to theposition it assumes when the tank is 30 full.

Now assume that the conducting fluid, viz. the water is discharged fromthe tank. As soon as the level of the water drops below the electrode I4a zero potential is applied to thegrid 48 of the vacuum tube 49, theplate current of said 35 tube drops, the relay 51 opens, and the motor42 starts running in the opposite direction from hat in which itpreviously ran, until the arm correct indicating position in front ofthe dial 45. 4

The electrode 8 is a common lead and the'level of the electrode 9 is thelowest point in the tank which can be read. As the level'of the waterdrops the switch arms 38 and 39 successively enuntil the arm 38 finallyengages the terminal member which is connected by the wire iii to theelectrode 8. A positive potential is then applied to the grid 48 of thevacuum tube 49, the plate current of said tube rises and the relay 51closes and stops the motor. At this time the level of the water is belowthe electrode 9, a zero potential is applied to the grid 52 of thevacuum tube 53, the plate current of said tube is lowered and the relay55 opens.

.In general, when one relay is open and the other closed the motor doesnot run. When both relays are closed the motor turns in one direction,and when both relays are open the motor tums' in the opposite direction.The indicator 6 moves when the motor is in operation and stops when themotor stops, and the entire operation of the apparatus is automatic.

During the operation of the device the operation of the split phaseelectric motor 42 is con- 7 trolled by the relays 55 and 51 as follows:Assuming that conditions in the container 5 are as illustrated in Fig.1, and that the switch arms 38 and 39 are contacting with the terminalmembers 38 and 3! respectively, there is a positive tubal potentialapplied to the grid ll or the vacuum through the conducting fluidbetween the el trodes I and I4. This positive gridpo tential causes theplate eurrentoi the'tube 4! to and. the relay l'l is thereiore energisedas indicated in Fig. 1. The electrode I beini located in anon-conducting fluid, viz. the air the motor will be energized androtate the switch until they contact with the terminal members .8! and84 respectively when the motor will stop arms 38 and II in unison in aclockwise direction because the terminal I4 is isolated. A zeropotential will now be applied to the grid 52 0'! the vacuum tube It andthe relay lili will be deenergized.

Now assume that the switch arms so and as are in contact with theelectric terminals 24 and 26 respectively and that the conducting fluid8 has dropped below the electrode a. Under these conditions a zeropotential is applied to the grid B2 of the vacuum tube," and the relayIt is de-energlzed. As the terminal member 24 is connected to the wireIt which in turn is con-. nected to the electrode 8 there is a positivepotential applied to the grid .oi the vacuum tubeand the relay I1 isenergized.

When both grids l8 and 52 have'a zero potential applied thereto, bothrelays 51 and 55 are de-energized. At this time the wire 83 from thesource of electric supply connects with the wire 60 to the wire 84 andto the motor 42; andthe lead 88 from the split phase winding of themotor I 42 is connectedto the wires 82 and 65, and under theseconditions the motor will rotate the arms 38 and in a counterclockwisedirection.

It has hereinbei'ore been stated that any type of reversible electricmotor with suitable relays may be used, and it will be apparent thatdifleren: types oi motors will require difle'rent wiring connections,all of which are well known to thosev skilled in the art and are withinthe scope of this invention.

'Iclaim: a 1. Liquid level responsive means comprising,

. in combination, a series of electrodes adapted to be positioned atdifferent levels within a container and exposed to a liquid thereinhaving electrical conductivity, a switch shiitable intm circuit withvarious of said electrodes, a gauge,

means in circuit with a. source of electricity for operating said switchand gauge in unison, vacuum tube means including plates, and grids incircuit, with the switch, and means responsive I &

arms and gauge. 3. Liquid level responsive means comprising,

to change in the plate circuits of said vacuum tube means forcontrplling the, operation of said switch and gauge operating means.

2. Liquid level responsive means comprising, in combination, a series ofelectrodes adapted to be positioned at diiierent levels within acontainer and exposed to a liquid therein having electricalconductivity, a switch including terminals in circuit with saidelectrodes, and arms I shiitable to contact various of said terminals, agauge, means in circuit with a source oi electricity for operating saidswitch arms and gauge in unison, vacuum tube means including plates, and

grids in circuit with said arnis, and relays in=plate circuits of saidvacuum tube means for controlling the operation of the actuating meansfor said in combination, a series 0! electrodes adapted to be positionedat different levels within 'a container and exposed to a liquid thereinhaving elec-- trical conductivity, a series of terminals connected tosaid electrodes, and switch arms shittable to contact various of saidterminals, a gauge, a motor ,in' circuit with a source of'electricityfor operating said switch arms and gauge in unison, vacuum tubesincluding plates, and grids in circuit with said switch arms, and meansresponsive to change in the plate circuits 01 said vacuum tubes forautomatically controlling the operation of said motor.

4. Liquid level responsive means comprising,

in combination, a series of electrodes adapted to be positioned atdifierent levels within a container a,nd exposed to a. liquidthereinhaving electrical conductivity, a switch including a series of terminalsconnected to said electrodes, and

arms shiftable to contact various of said'terminals, a gauge includingan indicator,a reversible electric'motor in circuit with a source ofelectricity for rotating said switch arms and indicator in unison,vacuum tube means including plates, and grids in circuit with saidswitch arms, and means responsive to change in the plate circuitsof-said vacuum tubes for automatically controlling the operationoi saidmotor.

5. Liquid level responsive means comprising, in combination, a series ofelectrodes adapted to be positioned at diflerent levels within acontainer and exposed to a liquid therein havingelectrical'conductivity, a shaft, 9. switch including a series 0!terminals connected to said electrodes,

, and arms fast to said shaft and arranged to en- 'gage adjacentterminals simultaneously, means to insulate said arms' one from theother and ir'om said shaft, a gauge including an indicator fast to theshaft, a reversible electric motor in circuit witha source 01'electricity for rotating the shaft, vacuum tubes including plates, andgrids in circuit with said switch arms, and relays-in the plate circuitsof the vacuum tubes for automatically controlling the operation of saidmotor.

GORDON E. EWER'IZ.

